Direct analyte-probed nanoextraction for document ink analysis

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The analysis of ancient documents, pictures, archeological pieces and related added-value samples is a challenging issue for any analytical chemist. The unique character of the samples and the priceless values of most of them require the sampling of a very small quantity to obtain as much information as possible. Undoubtedly, the direct analysis or the use of non destructive analytical techniques must be the first option for the researchers. But not the only one!! Our loved microextraction techniques could play a relevant role in this scientific field as they are able to maximize the amount of information obtained from a very low sample amount.

Recently, The Analyst journal has published a research carried out by our colleagues from the University of North Texas dealing with the potential of direct analyte-probed nanoextraction (DAPNe) coupled to different instrumental techniques for the determination of the authenticity of documents (1). The ink used for writing the manuscript is the target of the study. DAPNe coupled to nanospray ionization mass spectrometry extracts ultratrace amount (as low as 300 attograms) of analyte using a single solvent droplet with minimal effect on the document integrity. Indeed, the ink acts as a barrier between the extractant and the paper, thus increasing the time needed for soaking the paper and giving time the analyte to migrate from the ink to the solvent. That's really amazing!!. The use of nanomanipulator control the exact position of the droplet on the document.

However, there is still a question you are wondering. We are going to analyze a very small region of the document and from this analysis we want to obtain information about its authenticity. So, the immediate questions is how to select this sampling (or measuring) place. The answer is quite simple as we can use other non-invasive, portable analytical techniques to screen the document surface and identify the potential manipulation of the writing. In this regards, Raman spectroscopy or fluorescence microscopy are very useful.

We have really enjoyed the reading of the article and the excellent examples provided by the authors. We hope this excerpt will also awake your curiosity. Enjoy this piece of science as we have already done.

Reference:
(1) Investigation of falsified documents via direct analyte-probed nanoextraction coupled to nanospray mass spectrometry, fluorescence microscopy, and Raman spectroscopy. Link to the article

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